Welcome to the E46Fanatics forums. E46Fanatics is the premiere website for BMW 3 series owners around the world with interactive forums, a geographical enthusiast directory, photo galleries, and technical information for BMW enthusiasts.

You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.

I've got a 330 6sp and just upgraded my diff to an 3.15 unit and I would like to eventually to with a 3.46 rear. I still do a lot of long distance highway cruising in my car so I would like to keep my RPMs down and MPG up.

The 6sp has a .85 6th gear. I was wondering if replacing the .85 6th gear with something taller is an option? (Maybe a .68 6th gear?)

This is actually a really good idea. The same low end as a 3.46 rear, with the gas mileage of a 3.07 in 6th gear. Id imagine you would have to find the same trans that's in another car with this taller 6th gear and have a real tranny guy swap over 6th. I highly doubt there's anyone actually making this gear, and its not really something id recommend doing your self. It might end up costing a lot more than its worth to have done.

This is probably not a cheap project but I think it would be worth it. Its as close as you can get to having your cake and eating it too. I'm pretty sure that you'd need to get some sort of custom gear made.

I am going to contact Metric Mechanic about this. I am open to suggestions on other potential rebuilders that could do this.

well its more like paying for the fuel your saving up front. Do the math and I'm sure you'd have to drive an INSANE amount of highway miles to recoup your initial investment. I mean if your trying to be green that's fine I guess but I just don't see it paying off. What I would do is find another trans that would drop in with a similar 6th gear but tighter 1-5, and use the 3.15. It would probably cost you the same if not less money.